A clinical need exists for a dosage form for delivering an oral blood-glucose lowering drug to a patient needing this therapy. Glipizide is an oral blood-glucose lowering drug and it is indicated for the control of hyperglycemia and its associated symptomatology in patients with non-insulin dependent diabetes mellitus. Glipizide is useful therapeutically as an oral hypoglycemic drug because it stimulates insulin secretion from the beta cells of pancreatic-islet tissue, it increases the concentration of insulin in the pancreatic vein, and because it exhibits extrapancreatic action such as the ability to increase the number of insulin receptors.
Glipizide is known chemically as N-[2-[4-[[[(cyclohexylamino) carbonyl]amino]sulfonyl]phenyl]ethyl]-5-methylpyrazinecarboxamide. Glipizide is a white, odorless powder with a pKa of 5.9, and it is insoluble in both water and alcohol. These physical and chemical properties of glipizide do not lend the drug to formulation into a desage form that can administer glipizide at a controlled and known rate per unit time. The properties of glipizide are disclosed in Martindale The Extra Pharmacopeia, 29th Ed., p 390, (1989); and, AHFS Drug Information, pp 1741-45, (1989).
In the light of the above presentation, it will be appreciated by those versed in the pharmaceutical dispensing art to which this invention pertains, that a pressing need exists for a rate-controlled dosage form that can deliver the valuable drug glipizide to a patient in clinical need of blood-glucose lowering therapy. The pressing need exists also for an oral dosage form that can deliver glipizide at a controlled rate in a substantially constant dose per unit time for its beneficial therapeutic effects, and remain substantially independent of the changing environment of the gastrointestinal tract. It will be appreciated further by those skilled in the dispensing art, that if such a novel and unique dosage form is made available that can administer glipizide in a rate-controlled dose over time, and simultaneously provide blood-glucose lowering therapy, the dosage form would represent an advancement and a valuable contribution to the medical art.